Quote from makosgu:
The clean ratio is 12 YM vs 5 ES which works out to $60/tick. However, the technicality is with regards to how many YM points occur within a single ES tick (.25 points). Usually there is about 2-4 YM points for every .25 ES points. Personally, I use a 1:1 ratio for all futures since the correlation for nearly all index pairs > .95. Any typical scattered plot makes this plain and simple to see. Plot charts make super charts for pair trading... I stumbled on this aspect as a way of dealing with currency pairs. It's more boring than my usual trading but then again, the probability space is very confined. It only takes a very beginner level understanding of what correlation looks like in a plot in order to make this work in real time.
Kind REgards,
MAK